However, bonsai require a lot of care and feeding just to survive, including extensive pruning to thwart natural growth instincts. Without that pruning, the tree gradually consumes all of the soil’s nutrients and starves. All this intervention turns what should be a robust, independent tree into a fragile hothouse flower, subsisting on life support. At this juncture, even if it was freed from its constraints, this tree could never match the size of its wild counterpart. It’s a neat inversion of the usual relationship between man and nature, but like seeing a bored tiger at a zoo, it’s also a bit sad to see.

Natural systems also impose limits on their own sustainable growth, of course. Cycles see growth culminating in decline and death, then renewal and evolution. But nothing that’s alive stands perfectly still.

Those who propose to stop growth should have the humility to acknowledge that doing so will change the very nature of growing things. By giving themselves free rein to change the city, they are placing a tremendous burden on the resources of future generations.

In a recent speech to District Department of Environment employees, Mayor Muriel Bowser offered some warm words about Sustainable DC — but fell short of a full-throated endorsement:

The decisions that we make are often, I would always say, 50 year decisions… The decisions we make around transportation options, whether we put something someplace or not — again, 50 year decisions. What is clear is that we’re making decisions right now that affect the next generation, and shape the options for the generation after that.

We have to be very careful in government about how we distribute our resources, and how we take care of the community. We inherited it, and we have to leave it better for the generations that follow us…

I inherited the past successes… I inherited some good things, and one of those good things was Sustainable DC. And so what I know Tommy [Wells] will do with me is make recommendations on all the things we should keep, all the things we should push harder on, the things we have to add, and if there are things we have to change or delete we should do that too…. I was elected for a fresh start, not a start all over, and so we want to make sure that we’re building on the successes of your hard work… and push the District even farther.

Just to put one of those performance goals into a global perspective, Sustainable DC has twin goals of increasing the District’s population by 40% and shifting 75% of commute trips out of cars — baseline goals that MoveDC started with, and crafted an implementation strategy around. Alex Block points out that this is certainly doable, but it isn’t easy.

To do so will require more than doubling transit capacity, almost tripling bike capacity, and cutting car capacity by 7%. It would avert over one milion VMT every weekday — which (with current emissions factors, which assume today’s technology) would cut 580 tons a day from DC’s carbon emissions, more than 3X as much as the reviled Capitol Power Plant puts out.

Smart growth policies like MoveDC are a fine example of acting locally while thinking globally, as these are local policies that would have global consequences. The National Research Council & TRB estimate that a national shift towards denser development — including shifting more population growth into the District from the suburbs — would cut CO2 emissions from driving by 11% by 2050, even before any change in vehicle technology. That’s 132 million metric tons of CO2 each year, an amount exceeding all coal emissions from DC, Maryland, Virginia, and West Virginia. Or, put another way, smart growth cuts driving, which could cut as much CO2 as shutting down all of our region’s coal power plants.

Of course, we will absolutely need to do both — and much more — if we’re to have any hope of avoiding a certain existential threat to DC’s future. But only smart growth and energy efficiency cut emissions over the long run, and pay for themselves in the short run.

Bellevue was not one of the “suburban vibrant centers” examined for a NAIOP report on office occupancy trends.

Some recent reports left me appreciative of their aims and ends, but not exactly how they got there, and in particular with how other analyses have defined key terms.

1. The Living Community Challenge certainly provides an inspiring goal to reach for, notably in its use of elegant performance criteria that broadly require “net positive” environmental performance on site — broadly, that new developments can strive to shrink their ecological footprints to fit within their actual footprints. It also pretty seamlessly integrates the Transect throughout, and in a balanced way that sometimes rewards and sometimes penalizes both ends of the spectrum.

However, having participated in the creation of LEED for Neighborhood Developments, it’s telling that some of the same battles in that scheme have emerged within this one. Prescriptive approaches still occur throughout, and some of the personal-health ones are somewhat wishy-washy. (The emerging science of health impact assessments may have been a useful complement here.) The equity section (“petal”) has a lovely intro, but its imperatives don’t address many social criteria — affordable housing is a notable omission — and almost entirely use prescriptive standards. Another long-running debate was over the use of prerequisites in the rating scheme: It seems strange that a baseline, “Petal Community” certification can be done while ignoring a majority (four of the seven) of the petals.

I’ll be interested to learn more about the Challenge in the coming weeks, and to see how others feel about whether it’s rigorous and balanced.

2. Kriston Capps brings up Mikael Colville-Andersen’s term “magpie infrastructure” in a recent CityLab piece. Bicycle and pedestrian infrastructure, examples like the Bloomingdale Trail aside, rarely needs architects’ attention — their structure-first solutions are usually fundamentally anathema to bicyclists’ lazy inclination to not climb hills. By and large, people should be encouraged to stay at grade, and landscape architects and engineers should be entrusted with their care.

Closer to MCA’s home, the current BIG exhibit at the NBM includes Loop City (video; skip to 2:30), a proposal for an elevated rail loop around Copenhagen + Malmo. The proposal lifts up the stations so that trains decelerate on the approach and accelerate as they exit — a clever idea lifted from subways like Montreal’s. When done below-ground, this brings trains closer to the surface just where they’re needed, but when above-ground, the same approach antagonizes the energy needs of the passengers (who need to climb ever-higher escalators to get to the platforms) and the energy needs of the trains.

Another obvious flaw is that the proposal repeats the Corbu-in-Algiers mistake of thinking people would want to live in flats beneath a railway, without realizing that below-the-tracks spaces are almost always only valuable in situations (I’m thinking in Ginza, the Viaduc des Arts, or 9 de Julio) where such space is just the cheapest way of getting valuable ground-level, street frontage. Even maglevs are pretty awful to stand right underneath.

3. NAIOP recently published a report offering slight encouragement to the notion that office users are increasingly choosing mixed use environments — namely, 24-hour CBDs and 18-hour “suburban vibrant centers” (their terminology, not mine) — over single use suburban office parks. Their findings indicate that rental rates are indeed higher in CBDs, but that CBDs haven’t seen as much absorption as suburbs, whereas “vibrant” parts of suburbs had a verifiable edge in the leasing market. There’s certainly plentiful anecdotal evidence, and this has been the mantra of “Emerging Trends” and other qualitative reports for quite some time, but I’ve seen few attempts to quantitatively analyze the phenomenon.

Yet the two sets were compared quite differently. The comparison of CBDs vs. suburbs was strictly quantitative, an approach that didn’t control for the quality of the urban environments — downtown absorption was hurt by including a great many “dead” downtowns (Dayton, St. Louis, Hartford) among the comparison set. Most of the liveliest downtowns have seen strong positive absorption, since it’s less the CBD location than the mixed-use amenities that draw users.

The “vibrant centers,” on the other hand, were compared using a robust paired-case approach: single-use suburban areas were paired with mixed-use suburban areas within the same part of town. They even came up with a pretty strict definition of such centers and their comparison sites, using Walk Score and building-level maps. This better methodology dives into why people are migrating towards such sites, and goes beyond the not-terribly-nuanced submarket definitions found in typical office market reports.

Although the lower absorption figures for CBD office may look discouraging at first glance, it’s necessary to consider both that higher rents might result in tenants using CBD space more economically. Square feet don’t necessarily correspond with people, much less dollars. (Edit 26 Feb: City Observatory has a new report indicating that job growth has indeed been more robust in CBDs than in suburbs.) In addition, the supply constraints on new downtown office might suppress demand from space-hungry users — e.g., many large companies are expanding both in San Francisco and Silicon Valley, but adding more jobs in the Valley where construction isn’t limited by constraints like Prop M.

4. For good measure, here’s one instance where the methodology and the results both turned out okay: Governing’s recent analysis of gentrification at the Census tract level. The scale of the analysis is correct, the results pass the smell test, and the variables used (rankings of changes in household income and physical [home values] and cultural capital [college attainment]) seem reasonable.

30 meters of sea level rise would wipe out most of the L’Enfant City, put the White House underwater, and leave the Capitol on a little island — but it could still be managed by damming the Potomac River at key locations, like Quantico or Mason Neck.

Of the world’s major coastal-plain cities, Washington, Rio, and London are among the few that could conceivably be saved by damming estuaries, although I’m sure the Japanese will still try. (Or maybe Houston.)

The same can’t be said for Philadelphia, where the Delaware has a very broad valley, or even New York, where dams at Verrazano Narrows and Arthur Kill will have to be supplemented by very extensive construction to block Long Island Sound. Boston either becomes an archipelago or a polder at a mere 7m of SLR. Even Montreal faces serious property loss over 20m; at 30m Beijing becomes coastal and tides could reach Lake Champlain and the Caspian sea.

Much more than 30m, like the 60m these guys have in mind, and most everything on the east coast below the fall line would be gone. Even dams at the Golden Gate and St. John’s would no longer protect San Francisco or Portland. That’s when inland real estate might become rather more valuable.

Surprisingly, my river-view apartment should be okay up to +10m or so even without a downstream barrier.

I found some quotes I’d scribbled down from a New Republic event last December (link has streamable video of the entire event) about how state and local governments are responding to climate change. The first panel, in particular, had a refreshing focus on the built environment, thanks to two remarkable mayors who truly understand the value of building sustainable communities.

“Land is inexpensive [here], so it’s easy for lenders to say, ‘let’s just build sprawl.’ But cities end up having to support all that infrastructure: for instance, it costs $7 million to upgrade a mile of road.”

“The real challenge is in the suburban development pattern areas. We threw out 10,000 years of city planning expertise… The new cities of the last 50 years frankly don’t work so well.”

On how Carmel financed the higher cost of downtown development, including structured parking: “Developers, in my experience, are quite willing to build anything they think they can make money on. We reached out very purposefully to the lending community, brought them into the discussion. It got a lot easier [once they realized that] you can borrow against that added [capital] cost, because it adds value in the end.” (Here’s a photo tour of downtown and some new neighborhoods; as with a lot of greenfield NU, the architecture could be better, but at least the urban design is well-informed.)

Bob Dixson, Mayor of Greensburg, Kansas — a gem of a speaker who seriously deserves to be on the lecture circuit.

Reframing sustainability: “The right, prudent, and responsible thing to do for future generations, so that future generations can experience the same great nation that we have.”

“Are you a renter of your community or an owner? Will someone else take care if it for you or will you step up and volunteer? Are we going to own our issues or just rent them, and expect Pennsylvania Avenue to take care of it?”

“We can get back to being front porch people and have true conversations. The best way to prepare for a disaster is to have conversations and community.”

“We had all those [standard engineering] manuals in city hall, but then the wind came and blew all those manuals away.”

“The people of the West actually favor the EPA, it’s just that their representatives don’t.”

“Vast pools of private capital are waiting on the sidelines because of policy uncertainty. Putting a price on coal at the state level will create certainty, but instead [Congress] will keep debating it and create more uncertainty.”

“I don’t think that a lawsuit is a constructive thing against Kentucky. Are there coal lessons to be learned from other [rural] transition economies, like tobacco?”

Perhaps big changes to utility regulations are easier than small ones: ” ‘We don’t want to work against you, utilities, we want to work with you.’ Could public[ly owned] utilities lead the way? We need to redesign how we rate-base those things that you want us to do.”

The right thing in climate policy for all the big countries is a carbon tax, which is simpler and less vulnerable to fluctuations in emissions than cap-and-trade schemes.” – The Economist

A recent discussion spawned the idea of implementing a carbon tax within DC, and so I wrote up this brief.

– What and whom would a carbon tax affect?
A carbon tax, technically a tax upon the carbon content of energy and fuels, would primarily affect electric generation, gasoline & diesel, and heating fuels (natural gas, fuel oil). A narrower tax could affect only fuels, or electricity. The UK’s carbon tax, for instance, taxes various energy sources at differing rates.

Of carbon emissions within DC proper in 2010, natural gas was 54.6% and petroleum 45.2%. Because DC imports all of its electricity, it has the least carbon intense economy among the states, emitting 91.6% less CO2 per dollar of GDP than the US average. This does not, however, include fuel burned for electricity used by DC end users; 59.2% of DC electricity originated from fossil fuel generators.

– Have carbon taxes been implemented elsewhere?Yes, several jurisdictions have. Finland and Sweden were first, in 1990 and 1991. In North America, the provinces of British Columbia and Quebec have carbon taxes, as does the city of Boulder (on electricity only). Dozens of multinational corporations, including most oil majors, use an “internal carbon price” to evaluate corporate decisions: ExxonMobil’s is $60/ton.

– How have these fared?British Columbia’s carbon tax, unique in its broad reach even though the province works within the framework of a high-carbon-emitting country, “has been remarkably effective in reducing fuel use, with no apparent adverse impact on the province’s economy,” according to a University of Ottawa study. GDP growth paralleled Canada’s, income tax rates fell to the lowest nationwide, and fuel consumption fell by 17.4% per capita.

– Have carbon taxes been proposed in U.S. states?A bill has been introduced in the Massachusetts legislature, and a ballot measure is currently collecting signatures. In Washington state, Governor Jay Inslee has specifically directed a legislative commission to study a carbon tax, and an NGO has proposed draft legislation.

– What level of tax would be appropriate?
An easy guideline for measuring the impact of a carbon tax is that a tax of $1 per ton of CO2 results in just less than 1¢ in tax per gallon of gasoline. DC’s current gas tax rate of 23.5¢ per gallon thus implies a tax rate of $27.98/ton of carbon dioxide. (Maryland’s gas tax is now 32.10¢ per gallon.) This rate is very similar to the C$30/ton that British Columbia charges, and near the midpoint of the $5-65/ton “social cost of carbon” price suggested by the White House.

– Where do proceeds of carbon taxes go?
In most cases, as in British Columbia, carbon taxes are a “tax swap,” whereby other taxes — notably on income, capital, etc. — are reduced. Some bills, like that proposed by Citizens Climate Lobby, feature a “dividend,” or direct rebate back to taxpayers. Sometimes, climate actions are funded with a portion of proceeds as well; the Massachusetts bill, for instance, directs $90 million in revenue towards transportation debts and 10% to clean energy. In DC, ambitious plans have been launched, but not yet funded, for transit expansion (by WMATA and DC) and for cutting emissions, and a carbon tax would be one way of funding implementation of those plans. (Boulder’s tax was implemented to fund its climate action plan.) In addition, DC currently pays its annual operating subsidies for both WMATA ($275 million in FY2014: $58M bus, $42M rail, $22M paratransit) and DDOT transit out of general funds, and a carbon tax could be a stable, dedicated source of transit operating funds.

– Who are winners and losers?
A carbon tax that includes electricity would have a much broader base and thus wider impact. It would primarily affect the office sector, and as such mostly commuters, but it might also attract Congressional attention. A carbon tax solely on fuels would mostly impact building heating/cooling; again, this would largely fall on offices, but also on DC residents’ heating bills.

Although a carbon tax typically is somewhat regressive, there are many ways to design a carbon tax to mitigate impacts on lower income consumers. In particular, a DC carbon tax could use targeted measures to offset higher home heating costs for low income residents: income tax credits, weatherization or LIHEAP assistance, and transit improvements.

The first post in the watershed series mentioned that Morus alba (white mulberry) is a common invasive understory tree found at the edges of lawns along the Washington Channel, particularly along the unmown verge beside the fences that ring East Potomac Park’s recreation facilities. Given a chance, these shrubs will grow into a smallish tree of up to 15 meters, with a peculiar combination of lobed leaves on young shoots and heart-shaped leaves on older shoots. Its copious blackberry-looking fruits , which can disperse an estimated 20 million seeds per tree, make a convenient food source for birds and maybe humans — or else they leave a sticky purple mess on the walkways below.

But wait, mulberry? Isn’t that what silk is made from? How did that end up here?

What is this weed, and what does it have to do with the Opium Wars, Jefferson family wedding gowns, and deforestation in Ontario?

Silk production, or sericulture, was invented in China at least 4,000 years ago; legend says it was discovered by a princess who was strolling through the woods with a cup of hot tea. Young mulberry leaves are fed to silkworms, which spin silk threads around their cocoon as they metamorphose into moths. The cocoons are collected, boiled, and the threads are spun into fiber. China still accounts for most of the almost one million hectares (2.5 million acres) of mulberry under cultivation worldwide, according to the FAO, largely for silk but also for forage, wood, and even biofuel.

Yet sericulture (silk cultivation) requires that both mulberries and silkworms thrive in tandem. Mulberries obviously have adapted well enough to the local climate; thousands of years of domestication has selected for robust and easily grown varieties. The silkworms are a different story: they’ve been raised indoors for thousands of years, and thus have evolved into a very narrow ecosystem — they don’t even survive in the wild anymore, and require an exacting temperature range of 73-84° F, with high humidities, in order to thrive.

Silk was long one of the world’s most coveted agricultural products, and for centuries the world went to astonishing lengths to procure it from China.* Starting all the way back in Jamestown, Virginians attempted to get a cut of this lucrative trade by manufacturing silk: it seemed an ideal fit for the area’s warm climate and then-remote location, and potentially valuable both for the colonists and for British weavers. Yet while Virginia hews a bit closer to such temperatures than England, it isn’t exactly a room-temperature silkworm paradise. So while the robust mulberry thrived, fragile silkworms brought to Virginia didn’t, and instead Virginians profited off the native tobacco plant.

Thomas Jefferson’s family attempted silk cultivation at Monticello, and the results are telling. Above is “Mulberry Row,” the remnant of a lane lined with mulberry trees and, once upon a time, several buildings where slaves and other laborers did much of the work of the plantation. Obviously, the mulberry trees have done okay over the years — outlasting the buildings, for instance. The silkworms, though? Not so much. In 1811, Jefferson jokingly wrote to his granddaughter Cornelia,

your family of silk worms is reduced to a single individual that is now spinning his broach. to encourage Virginia and Mary to take care of it, I tell them that as soon as they can get wedding gowns from this spinner they shall be married. I propose the same to you that, in order to hasten it’s work, you may hasten home; for we all wish much to see you.

For what it’s worth, neither Mary nor Cornelia ever married, although I doubt her silkworm colony’s failure to generate enough silk for a wedding gown had much to do with that.

Silk was so valuable that Americans couldn’t be dissuaded by the industry’s failure in Virginia. Silkworms, as mentioned above, are fickle and highly adapted to the methods of Chinese sericulture; they feed almost exclusively on Morus alba, which as mentioned grows quite vigorously on Chinese farms. Eastern North America has a native variety of mulberry, Morus rubra, an understory plant suited to the area’s deep forests, but the silkworms rejected M. rubra feed.

Instead, colonists planted several Chinese mulberry varieties in hopes of keeping their silkworms happy. Colonial-era botanist William Bartram, in his travels through the South, noted dozens of instances of M. rubra but only one of M. alba trees — at a plantation near Beaufort, S.C. that was attempting sericulture (digitized book, pg. 308; location surmised between present-day Jacksonboro, S.C. and Savannah, Ga.). Later, Connecticut implemented various subsidy schemes, even including a cash bounty on planting Chinese mulberry varieties, and eventually succeeded at building a small silk industry in the 19th century.** (The Morus multicaulis mentioned in the Mansfield article is now recognized as a variety of M. alba.)

In the intervening centuries, the invasive M. alba has far outcompeted native M. rubra on its home turf: M. alba has spread much of the contiguous United States except for the desert Southwest, high plains, and taiga forest, and pushed M. rubra to endangerment in Connecticut, Massachusetts, and Ontario. Not only have widespread planting efforts like those in Connecticut spread M. alba far and wide, but it’s a tree that’s been honed by centuries of breeding for vigor, with a “high growth rate and great adaptability to adverse environments,” according to the Global Invasive Species Database: “M. alba and hybrids were evaluated to be consistently more fit than the native M. rubra in a laboratory study.” M. alba hybridizes with, and spreads root diseases, to M. rubra. Widespread deforestation and urbanization in eastern North America opened up countless opportunities for sun-loving, early-successional species like M. alba, while concomitantly destroying the deep shade that M. rubra adapted to.

* As a descendant of Cantonese merchants, perhaps I should be glad that these experiments failed? Oh, the complicated webs that history weaves for us!
** The mild success found in Connecticut indicates that perhaps it was less the climate, but Virginia’s lack of capital for indoor silkworm warms, that doomed the early industry.